1. Field of the Invention
The present invention relates to closures for chambers and, more particularly, to a closure for a chamber having an interior that can be placed under pressure, such as a sterilizer.
2. Description of the Prior Art
There exists a wide variety of chambers adapted for maintaining a positive pressure. An example of such a chamber is a sterilizer that operates under positive pressure during at least a portion of the sterilizing cycle. One disadvantage associated with the use of all such chambers, however, is the risk that a person will open the door of the chamber while its interior is under positive pressure; accordingly, workers in the art have devised closures that minimize such a risk.
One type of such a closure employs a door having a deformable member--such as a diaphragm or a lid--that is secured to an inner surface of the door. A portion of the deformable member is deformed by positive pressure present within the chamber and urged toward the exterior of the chamber. The movement of the deformed portion activates a locking mechanism which prevents a person from opening the door until the pressure falls below a predetermined minimum and permits the deformable member to assume its original undeformed shape. Although closures employing such a deformable member have enjoyed some success in solving the problem identified above, it is not possible to produce such members of consistent dimensions; for example, it is not possible to produce dished diaphragms of consistent depth. Accordingly, the effect of the same amount of pressure on the deformable members of a number of closures of the same design may vary greatly from one member to another causing nonuniform activation of the corresponding locking mechanism. The deformable members of closures of the same type will actually lock and unlock the door of a chamber at different pressures.
Further, known closures can operate effectively only by exerting a mechanically-compressive force on the seal between the door of the chamber and the chamber to prevent fluid leakage from the interior of the chamber. Such a restriction makes the closure relatively complicated, costly and difficult to use. Moreover, such a restriction highly stresses the seal during use of the chamber and, therefore, the seal must be replaced periodically.
A closure for a pressurized receptacle is disclosed in U.S. Pat. No. 4,159,063, issued to Weber et al. However, the closure disclosed in U.S. Pat. No. 4,159,063 employs a deformable member--an internal lid--to activate the locking mechanism and requires that compressive force be exerted on the sealing device to prevent fluid leakage from the interior of the chamber.
Accordingly, there exists a need for a closure for a chamber having an interior that may be placed under positive pressure that does not require that the sealing device of the chamber be placed under compressive force to prevent fluid leakage from the chamber and which does not use a deformable member to activate the locking mechanism of the closure.